Spark plug boot having high frequency electrical discharge suppression means therein



Oct. 12, 1965 D, JR 3,212,044

SPARK P BOOT HAVING HIGH FREQUENCY ELECTRICAL SCHARGE SUPPRESSION MEANS THEREIN 2 Sheets-Sheet 1 Filed April 5, 1963 //llrdww INVENTOR. Iva/7 E Cloud Jr:

J ,QTTORNE Oct. 12, 1965 I. F. CLOUD, JR 3,212,044

SPARK PLUG BOOT HAVING HIGH FREQUENCY ELECTRICAL DISCHARGE SUPPRESSION MEANS THEREIN 2 Sheets-Sheet 2 Filed April 5, 1963 INVENTOR. [Va/7 E C/aud Jr.

J arrow/5m United States Patent SPARK PLUG BGDT HAVING HHGH FRE- QUENCY ELECTRICAL DISCHARGE SUP- PRESSION MEANS THEREIN Ivan F. Cloud, In, Kansas City, Mo., assignor to Whitaker Cable Corporation, North Kansas City, Mo., a corporation of Delaware Filed Apr. 5, 1963, Ser. No. 270,968 Claims. (Cl. 338-66) This application is a continuation in part of application Serial No. 161,904 filed December 26, 1961, of the same title which has now been abandoned. The instant invention relates to electrical ignition apparatus, and more particularly to such apparatus wherein is provided means for suppressing the high frequency electrical discharge which accompanies the direct current arc during the firing of a spark plug.

Immediately following the direct current arc across the points of a spark plug in an internal combustion engine, there occurs an interval of high frequency, damped oscillatory, electrical discharges between the points of the spark plug. These discharges are known to result from the capacitor characteristics of the spark plug and the ionized state of the air or gas along the path that has just been traversed by the main or firing, direct current arc. Such high frequency oscillations are the cause of serious static or interference to radio equipment in the Vicinity of the engine.

Numerous attempts have been made in the past to eliminate the effects from such discharges. These efforts have taken different forms, including the incorporation of various resistances or inductances in series in the direct current lead from the distributor to the spark plug in an endeavor to dampen out such discharges so rapidly that they become inconsequential.

The dampening effect of such devices have been relatively successful, but the use of such devices has not met with complete commercial success because of certain structural limitations encountered in prior art devices. It is essential that a good mechanical and electrical connection be maintained since without such a connection, the functioning of the dampening means and the firing of the spark plug are impaired. Prior art devices have had inherent structural weaknesses which prevented them from being successful for the purpose.

Further, arcing between the connections and across the resistor or inductor was often encountered with heretofore known devices and in an effort to avoid such arcing and other disadvantages presented when a resistance or inductance was connected in the line, an attempt has been made to provide the necessary dampening resistance by constructing the ignition conductor of string impregnated with graphite. This construction has been found to be fragile and has a poor service life.

Accordingly, it is the most important object of the instant invention to provide structure for integrating means into an ignition line for suppressing high frequency electric'al discharges utilizing connectors which may be quickly and easily fabricated by efficient roduction methods, yet provide connections of a quality capable of withstanding severe stresses without adversely affecting the direct current required for proper engine ignition.

An extremely important object of the invention is the provision of a jacket of relatively inelastic, rugged material interconnecting the components of the suppressing structure to protect the structure from the stresses en- 3,212,944 Patented Got. 12, 1965 ice countered in operation and to guarantee a good mechanical and electrical coupling of the components at all times.

Another very important object of my invention is the provision of an electrical discharge suppressor assembly having means to restrict the flow of electricity to a path through the suppressor so that arcing between the connections and across the suppressor is eliminated.

A further object of the invention and in the achievement of the preceding object, is the provision of suppressor connections having only relatively smooth facing surfaces to eliminate opposed, sharp points or edges to further reduce any tendency for arcing across the suppressor.

Another object of this invention is the provision of connectors having novel side Wall configuration permitting tight press-fit connection with the ends of the suppressor and resultant cold flow of a part of the side wall metal Without appreciably diminishing the strength of the connectors.

A still further object of the invention is the provision of a molded, relatively flexible boot of insulation material enclosing the suppressor unit and its connectors to shield the unit from external forces and to prevent the introduction of moisture into the unit.

In the drawings:

FIGURE 1 is a side elevational view of electrical discharge suppressor structure showing the preferred embodiment of the principles of this invention, parts being broken away and shown in cross section to reveal details of construction;

FIG. 2 is a plan view of the structure of FIG. 1, the jacket and boot being removed for clearness;

FIG. 3 is a front elevational view of the spark plug coupler of FIG. 1;

FIG. 4 is a cross-sectional view along line 44 of FIG. 1;

FIG. 5 is a cross-sectional view along line 5-5 of FIG. 3;

FIG. 6 is a plan view of a second embodiment of the structure of the invention, parts being broken away and shown in cross section to reveal details of construction;

FIG. 7 is a side elevational view of a modified form of spark plug coupler;

FIG. 8 is a side elevational view of another form of spark plug coupler;

FIG. 9 is a side elevational view of still another spark plug coupler; and

FIG. 10 is a side elevational view of yet another form of spark plug coupler.

Briefly, this invention relates to apparatus for suppressing high frequency electrical discharges emanating from a spark plug and comprises a connector electrically coupled to one end of an ignition line. The coupler has an integral collar which receives in tight electrical and me.- chanical connection one end of an essentially cylindrical suppressor body and the other end of the body is electrically connected to an essentially cylindrical element in which it is received.

The element is integral with a plate which is secured to a generally tubular coupler adapted for electrical connection with a terminal of a spark plug. The ignition line connector and the coupler plate are disposed in opposed facing relationship and each is provided with a flat surface devoid of sharp edges or points. These fiat surfaces face one another and inhibit the tendency for discharging across the suppressor body. A jacket of durable, relatively inflexible material is molded around the components of the assembly and firmly locks the components against movement relative to each other, provides strength for the unit to resist breakage, and guarantees good mechanical and electrical connection of the components. A boot of relatively flexible, nonconductive material is formed in close encircling relationship to the entire suppressor assembly and prevents moisture and the like from entering the unit which would tend to conduct electricity across the suppress-or and thereby insures the flow of electricity through the suppressor body. The boot further functions as a protector for the assembled suppressor structure.

Referring initially to FIG. 1 which shows a preferred embodiment of the suppressor structure, the structure comprises a lead 12 adapted to be coupled to the distributor or the like of an electrical ignition system. Lead 12 has a conductor 14 and an outer insulating sheel or sheath 16. A connect-or broadly designated 18, has a pair of initially fiat sheets a and 20b bent to provide tubular wall 20. An end wall 22 is integral with side wall 20 at one end of the latter through a neck portion 24 and presents a flat face 26 having an opening 28 therethrough.

It will be noted from FIG. 1 that end wall 22 is bent to extend transversely across one end of connector 18. A collar 30 is integral with end wall 22 around opening 28 and extends into tubular connector 18. The flat face 26 of end wall 22 merges into the inner surface of collar 30 through an arcuate stretch 32 of a shoulder defining the opening 28 in end wall 22. Connector 18 is formed from conductive material and is connected to conductor 14 by means of a stretch 34 of the latter extending outwardly from shell 16 and bent back upon shell 16 where stretch 34 is clamped into firm surface engagement with the inner surface of tubular wall 20.

It will be readily understood, however, that any suitable means may be employed for electrically coupling connector 18 with conductor 14, as, for example, providing connector 18 with a lanced tab (not shown) which passes through the insulating shell 16 and into electrical contact with conductor 14.

An electrical discharge suppressor unit which is preferably a wire wound resistor, but may be a carbon resistor, coil or the like, has an elongated, relatively rigid, cylindrical body 36 having one end thereof received in collar 30. The end of body 36 is press-fitted into collar 30 to provide firm electrical contact between body 36 and collar 30, and to this end, it will be noted that end wall 22 is of substantially greater cross-sectional dimension than is collar 30. The greater dimension of end wall 22 allows for a certain amount of cold flow of the metal from end wall 22 as body 36 is press-fitted into collar 30 through opening 28 yet insures that neck 24 will have the required stability for supporting body 36 after the latter is connected to connector 18 through collar 30.

When a wire wound resistor is utilized for the electrical discharge suppressor unit as illustrated in the drawings, the operation of press-fitting the body 36 into collar 30 performs the additional function of stripping back the coating of varnish-like material from the resistance wire at the juncture of body 36 and collar 30. Thus, only so much of such coating is stripped from the wires as is necessary to insure good electrical contact, leaving the coating over the remainder of body 36 for holding the coils of wire in place and for insulating the coils from one another.

The opposed end of body 36 is similarly press-fitted into a cylindrical element 38 integral with a plate 40 extending upwardly from a coupler 42. As best seen in FIG. 5, plate 40 has a flat surface 46 which merges into inner surface 44 of element 38 through an arcuate stretch 48 of a shoulder defining an aperture 50 in plate 40. Flat surface 46 is disposed in facing relationship with flat face 26 of connector 18 and it will be noted that the radius of the opening 28 in end wall 22 is greater adjacent flat face 26 than adjacent the inner surface of collar 30. Likewise, the radius of aperture 58 through plate 40, is greater adjacent its outer flat surface 46 than adjacent the inner surface 44 of element 38. The greater cross-sectional thickness of plate 40 than of element 38, permits the cold flow of metal from plate 40 as body 36 is pressfitted into element 38 through aperture 50 and the relative rigidity and structural ruggedness of plate 40 and particularly, its connection through an integral neck 51 to a tubular sleeve 52 of coupler 42 is not impaired by the press-fitting process. The press-fitting and consequent electrical and mechanical coupling of the element 38 to the suppressor body 36 is identical to that heretofore described with respect to collar 30. It will be noted from FIG. 1 that element 38 is disposed on the opposite side of plate 40 from the side on which collar 30 is disposed on wall 22 so that element 38 is directed away from collar 30.

Sleeve 52 may be formed from a pair of plates 52a and 52b of initially flat material which are bent into arcuate configuration forming the side walls of sleeve 52. Sleeve 52 is adapted to be disposed over the terminal of a spark plug and, to insure a more effective electrical connection to the terminal, may be provided with indentations 54 disposed to frictionally engage the terminal. It will be understood, of course, that coupler 42 is likewise formed from electrically conductive material.

A jacket 53 of relatively inelastic material such as nylon or the like is disposed in covering relationship around the suppressor body 36, connector 18, plate 40 and ele ment 38. Jacket 53 may be molded around the suppressor and coupling assembly so that the inner configuration of jacket 53 conforms to the outer surface configuration of the assembly. It is of particular significance to note also that the annular rims of wall 22 and plate 40, respectively, are firmly embedded in jacket 53. To this end that portion of jacket 53 proximal plate 40 is provided with an enlargement 53a including an annular shoulder 53b engaging one face of wall 40 and an inwardly extending annular flange 53c engaging the opposite face of wall 40 to clamp the latter firmly in place. That portion of jacket 53 proximal connector 18 is of enlarged diameter and terminates in an integral tubular portion 53d extending into encircling relationship around insulating shell 16 of conductor 14. An annular shoulder 53e of jacket 53 engages face 26 of wall 22 and an inwardly extending, annular flange 53f engages the opposite face thereof to securely clamp wall 22 in fixed position.

The jacket material is formed to provide integral end walls 55 and 57 disposed in closing relationship across respective ends of the suppressor body 36 to completely encase the latter.

A boot 56 of nonconductive, generally elastic material such as plastic or the like, is formed around connector 18, body 36, coupler 42 and jacket 53 preferably by injection molding or the like to maintain a close bond to the outer surfaces of the jacket and assembly. If desired, an end 56a of boot 56 may be extended beyond connector 18 a short distance to bond to a portion of shell 16 of lead 12, and another end 5617 of boot 56 may extend beyond sleeve 52 and is cut away to provide a tubular skirt portion adapted to be disposed over a spark plug for shielding the latter.

It is desirable that sleeve 52 be provided with integral, outwardly extending tabs 59 which are embedded in boot 56 and serve to prevent separation of sleeve 52 from boot 56, particularly when sleeve 52 is subjected to relatively large stresses as may occur when the assembly is either coupled to or disengaged from a spark plug.

In the preferred embodiment of the invention as shown in FIG. 1, plate 40 is integral with the side wall of sleeve 52 at one edge of the latter and extends generally parallel with the longitudinal axis of the elongated, tubular sleeve 52. This permits a generally L-shaped disposition to structure and boot 56 is accordingly molded to generally conform to the L-shaped configuration of structure 10. In the embodiment illustrated in FIG. 6 of structure 110, however, the plate 140 of coupler 142 is bent transversely across one end of tubular sleeve 152 and permits a relatively straight line disposition of structure 110. Accordingly, boot 156 is molded to conform to the configuration of structure 110. A jacket 153 similar to jacket 53 is incorporated in structure 110 in the same manner as described with respect to structure 10.

A coupler 242 is illustrated in FIG. 7, having an element 238 extending in the opposite direction to element 38 of FIG. 1. Thus, element 238 extends toward connector 18 rather than away from the latter. Such construction is within the contemplation of the invention and might be preferred in some instances for ease of fabrication, strength of connection to body 36 or the like, but such construction is not as resistant to arcing across the outer surface of the suppressor as is the case with the embodiment of coupler 42 shown in FIG. 1.

Another construction for the receptacle connecting a coupler 342 to body 36 is shown in FIG. 8 as element 338. It will be noted that element 338 has an end wall 339 closing the end of element 338 remote from plate 340.

A still further form of the invention is shown in FIG. 10 as a coupler 442 having an upstanding plate 440. Body 436 of the electrical discharge suppressor is of a type having a cap 438 on the end thereof adapted to be connected to coupler 442 and, to this end, both electrical and mechanical connections are effected between body 436 and coupler 442 by means of a solder connection 443 between plate 440 and cap 438.

A still further form of the invention is shown in FIG. 9 wherein is shown a coupler 542 identical to coupler 442 but having a hole 541 throgh plate 540. Coupler 542 is connected to a cap 538 on suppressor body 536 by means of a pin 545 integral with cap 538 and extending from one end of the latter which passes throguh hole 541 and is enlarged on the opposite side of plate 540 to present a riveted head 547 or the like.

The connectors and the couplers of this invention may be quickly and easily fabricated by high speed and efficient production methods from initially flat strips of metal or other conducting material. The collars such as collar 30 of the connectors 18 and the elements such as element 38 of the couplers 42 may be stamped from the flat material and the generally tubular configuration of the connectors and couplers can be formed by a simple bending process. Additionally, the arcuate stretches of the shoulders defining the openings and apertures in the walls and plates respectively, permit ready integration of the suppressor bodies into the assembled structure by means of a press-fitting operation. To insure good electrical contact between the suppressor bodies and the connectors and couplers, the ends of the bodies may be provided with a coating of a suitable conductive material. The entire structure may then be placed in machines where the jackets 53 and the boots 56 are injection molded therearound. The fabrication operation may be performed entirely automatically and at high speed, yet the quality of the connections between the suppressor body and its connecting units may be maintained at a very high standard to insure long life to the suppressor structure.

In operation, sleeve 52 is electrically connected to a spark plug which receives energy from the distributor through conductor 14. The suppressor body 36 is made from material chosen to provide an amount of electrical resistance or inductance which is not great enough to prevent sufiicient flow of direct current energy to the spark plug to retard the efiicient operation of the latter. However, when the high frequency electrical discharge oscillations occur due to the ionized state of the air or the gas between the points of the spark plug following dis charge of the direct current arc, these high frequency discharges are choked out as they pass through body 36 and are effectively damped to prevent their interference with electronic equipment such as a radio or the like. No moisture can accumulate on the outer surfaces of the connectors, couplers or suppressor bodies because the jackets and boots are molded in close bonded relationship with such outer surfaces to exclude all materials from the suppression device which could render the latter inoperativ'e for the defined purp'ose thereof. The rounded, arcuate, outwardly flared configuration of opening 28 and aperture 50 in end wall 22 and plate 40, respectively, do away with any sharp edges facing one another and, since such sharp edges provide points at which electrical charges tend to accumulate, there is no tendency for arcing between connector 18 and coupler 42.

The jackets 53 and 153 are extremely important in guaranteeing both mechanical and electrical interengagement of the components of the suppressor assemblies even after prolonged exposure to high order mechanical stresses and vibrations which invariably are associated with physical connection to internal combustion engines. Heretofore available suppressor assemblies were universally deficient in this respect and were not widely accepted due largely to the tendency of their components to become meachincally separated resulting in electrical disconnection of the components and loss of suppression. Now, however, the jackets 53 and 153 of relatively inelastic material molded around the components firmly hold the components in place and positively prevent relative movement in any direction. The relatively elastic boots shield the components of the assemblies from external blows or the like and the relatively inelastic jackets impart rigidity to the assemblies to thereby resist any tendency for breakage. This is particularly advantageous as it permits utilization of a wire wound resistor having a ceramic core or utilization of a carbon resistor without unduly weakening the strength of the assembly.

Nylon has been selected as the preferred material from which the jackets are fabricated because of the ease with which it may be injection molded on the assembled components, its resistance to the high heat which often is attendant in close proximity with an internal combustion engine and because of its desirable physical qualities. In this latter respect, it is pointed out that the tensile strength of the material is good, it is relatively tough, and a very small amount of the material is sufiicient to obtain the desirable results heretofore mentioned.

It is contemplated that various types of electrical discharge suppression devices may be employed between connector 18 and coupler 42 of the present invention or the equivalent connectors and couplers of the other embodiments as shown and described herein, but the preferred suppressor comprises a wire wound device which has the effect of serving as an electrical choke to prevent broadcast of high frequency signals from the ignition system. The wire wound suppressor may have tubular metal connectors on opposed ends thereof to increase the area of electrical connection of the suppressor to the conductor connector such as 18 or the coupler 42. 'An alternative construction would provide a coating of silver or other conductive material at opposite ends of the suppressor and with a silicone or other similar composition being provided on the outer surface of the suppressor to maintain the coils thereof in proper spaced relationship and also serve as a protective layer thereover.

Wire wound resistors have been found to be particularly well suited for use in suppressors of the kind herein described because of their inherent characteristic of affording greater electrical impedance to alternating current of high frequencies than of low frequencies. This is exactly the result desired to dampen high frequency spurious alternating current electrical discharges without adversely'afiecting the supply of direct current ignition energy to the engine.

It is believed that the reason that a wire wound resistor presents increased impedance to current flow as the frequency of the alternating current increases is to be found in the so-called skin effect occurring at high frequency. Because of the magnetic field around the coil presented by the wire wound resistor, the electrons are caused to flow only on the outer portion of the wire. Since the current impedance is a function of the area of the path of flow, the restriction of the flow to such a relatively small area of the wire tends to increase the impedance.

As an example illustrating the effect of increased frequency on the impedance of a wire wound resistor having a direct current resistance of 22,000 ohms, the follow ing values were read on a Boonton Resistance-Reactance meter with current of the frequencies listed:

Frequency: Ohms impedance 1 mc. 22,500 5 mc. 27,000 mc. 36,000 50 rnc. 83,000 75 mc. 100,000

The following values were obtained by calculated extrapolation for the same wire wound resistor at higher frequencies.

Frequency: Ohms impedance 100 mc. 117,000 150 mc. 143,000 200 mc. 165,000 250 Inc. 185,000 300 mc. 202,000 400 mc. 234,000 500 mc. 260,000

Inasmuch as the ideal result sought to be achieved is the suppression of the high frequency alternating current discharges while at the same time permitting uninhibited flow of the direct current, it will be readily apparent that wire wound resistors are well suited for assemblies for ignition suppression. This is particularly true inasmuch as most of the undesirable spurious electrical discharges associated with the ignition firing of an internal combustion engine are in the relatively high frequency range.

Although the suppressor assembly of this invention has been described as a component part of the ignition harness which would presumably be securely attached to the ends of the spark plug wires at the time of fabrication thereof, it is contemplated by the invention that separate suppressor assemblies might be utilized. Specifically, it is anticipated that suppressor units comprising a coupler, a sleeve and a suppressor body along with the supporting jacket and covering boot will be constructed but not firmly attached to the end of the ignition wire at the factory. Instead, such assemblies would be distributed as an automobile accessory for incorporation into ignition wiring harness assemblies which have been constructed without such high frequency discharge suppression apparatus. Such accessory assemblies would, of course, be provided with reasonable attachment means (not shown) to be coupled with the end of the ignition wires in place of the connectors 18. The suppressor assemblies would then be coupled with the spark plugs as previously described.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In electrical ignition apparatus including a spark plug and electrical energy producing means, structure for suppressing electricalemissions from said spark plug and including:

(a) an electrical conductor adapted to be coupled to the energy producing means;

' (b) a tubular connector receiving one end of the com ductor in electrical connection therewith, said connector including an end wall disposed across the outer end thereof and a collar integral with the end Wall and extending into the connector, said collar having an inner surface and the end wall having a relatively flat face, said wall being provided with a shoulder defining an opening through the wall, the face merging into one end of the inner surface through an arcuate stretch of the shoulder with the area of the opening at the outer face being greater than the cross sectional area of the passage defined by the inner surface of the collar;

(c) a coupler adapted for connection to the spark plug, said coupler including a plate having a relatively flat surface and a tubular element integral with the plate and having an inner surface, the plate having an edge defining an aperture through the plate, the flat surface merging with the inner surface of the element through an arcuate stretch of the edge with the area of the aperture at the flat surface of the plate being greater than the cross sectional area of the passage defined by the inner surface of the element; and

(d) an elongated body for suppressing high frequency electrical discharges, one end of said body extending through said opening and being telescopically received in the collar in electrical connection therewith, the other end of the body extending through the aperture and being received in the element in electrical connection therewith, the fiat surface of the plate being disposed proximal the end wall of the connector with the element extending away from said end wall whereby only smooth surfaces of the connector and coupler are disposed in facingrelationship to prevent arcing therebetween.

2. Apparatus as set forth in claim 1 wherein is included a jacket of relatively inflexible material, said jacket interconnecting the plate and the wall for maintaining the wall and plate in fixed relative positions whereby electrical and mechanical connection of the coupler and connector to the suppression body is insured.

3. Apparatus as set forth in claim 2 wherein is included a boot of relatively flexible, electrically insulative material molded around the connector, coupler, body and jacket.

4. In electrical ignition apparatus including a spark plug and electrical energy producing means, structure for suppressing electrical emissions from said spark plug and including:

(a) a lead comprising an electrical conductor adapted to be coupled to the energy producing means and an insulating sheath disposed in surrounding relationship to said conductor;

(b) an electrically conductive coupler adapted to be operably connected to the spark plug;

(0) high frequency electrical discharge suppression means having an elongated body;

(d) a connector electrically and mechanically coupling the suppression means to said conductor, said connector including atube provided with wall structure telescoped over the lead and in clamping engagement with said sheath under sufficient force to provide a strong mechanical bond between the tube and the sheath, an end wall disposed across the outer end of said tube, and a collar integral with the end wall and extending into the tube, said end wall having an outwardly flared opening therethrough registering with said collar and defining a passage therewith telescopically receiving one end of said body; and

(e) means electrically and mechanically connecting the coupler to the suppression means.

5. Apparatus as set forth in claim 4 wherein said collar has an inner surface, said end wall having a relatively flat outer face and being provided with a shoulder defining said opening, said face merging into one end of 9 said surface through an arcuate stretch of the shoulder with the area of the opening at the face being greater than the cross sectional area of the portion of said passage defined by said surface.

References Cited by the Examiner UNITED STATES PATENTS 1,998,710 4/35 Doane 338-66 2,163,771 6/39 Alden 339-223 10 11/45 Stoflel 338-66 10/48 Buchanan et a1 339--223 5/57 Woofter 339-26 9/61 Noir 31558 1/ 63 Candelise 339-26 FOREIGN PATENTS 4/60 Great Britain.

RICHARD M. WOOD, Primary Examiner. 10 

1. IN ELECTRICAL IGNITION APPARATUS INCLUDING A SPARK PLUG AND ELECTRICAL ENERGY PRODUCING MEANS, STRUCTURE FOR SUPPRESSING ELECTRICAL EMISSIONS FROM SAID SPARK PLUG AND INCLUDING: (A) AN ELECTRICAL CONDUCTOR ADAPTED TO BE COUPLED TO THE ENERGY PRODUCING MEANS; (B) A TUBULAR CONNECTOR RECEIVING ONE END OF THE CONDUCTOR IN ELECTRICAL CONNECTION THEREWITH, SAID CONNECTOR INCLUDING AN END WALL DISPOSED ACROSS THE OUTER END THEREOF AND A COLLAR INTEGRAL WITH THE END WALL AND EXTENDING INTO THE CONNECTOR, SAID COLLAR HAVING AN INNER SURFACE AND THE END WALL HAVING A RELATIVELY FLAT FACE, SAID WALL BEING THE END WALL HAVING A SHOULDER DEFINING AN OPENING THROUGH THE WALL, THE FACE MERGING INTO ONE END OF THE INNER SURFACE THROUGH AN ARCUATE STRETCH OF THE SHOULDER WITH THE AREA OF THE OPENING AT THE OUTER FACE BEING GREATER THAN THE CROSS SECTIONAL AREA OF THE PASSAGE DEFINED BY THE INNER SURFACE OF THE COLLAR; (C) A COUPLER ADAPTED FOR CONNECTION TO THE SPARK PLUG, SAID COUPLER INCLUDING A PLATE HAVING A RELATIVELY FLAT SURFACE AND A TUBULAR ELEMENT INTEGRAL WITH THE PLATE AND HAVING AN INNER SURFACE, THE PLATE HAVING AN EDGE DEFINING AN APERTURE THROUGH THE PLATE, THE FLAT SURFACE MERGING WITH THE INNER SURFACE OF THE ELEMENT THROUGH AN ARCUATE STRETCH OF THE EDGE WITH THE AREA OF THE APERTURE AT THE FLAT SURFACE OF THE PLATE BEING GREATER THAN CROSS THE SECTIONAL AREA OF THE PASSAGE DEFINED BY THE INNER SURFACE OF THE ELEMENT; AND (D) AN ELONGATED BODY FOR SUPRESSING HIGH FREQUENCY ELECTRICAL DISCHARGES, ONE END OF SAID BODY EXTENDING THROUGH SAID OPENING AND BEING TELESCOPICALLY RECEIVED IN THE COLLAR IN ELECTRICAL CONNECTION THEREWITH, THE OTHER END OF THE BODY EXTENDING THROUGH THE APERTURE AND BEING RECEIVED IN THE ELEMENT IN ELECTRICAL CONNECTION THEREWITH, THE FLAT SURFACE OF THE PLATE BEING DISPOSED PROXIMAL THE END WALL OF THE CONNECTOR WITH THE ELEMENT EXTENDING AWAY FROM SAID END WALL WHEREBY ONLY SMOOTH SURFACES OF THE CONNECTOR AND COUPLER ARE DISPOSED IN FACING RELATIONSHIP TO PREVENT ARCING THEREBETWEEN. 